MRI-PET Radiotherapy System for In Vivo Dose Verification
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Solution Overview
Problem
Current radiotherapy systems, particularly particle therapy, face challenges in accurately measuring and verifying in vivo dose deposition due to uncertainties in beam energy and tissue density, leading to potential under-treatment of tumors and over-treatment of healthy tissues.
Innovation Solution
A combined Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) system is used to determine in vivo dose deposition by positioning a PET detector between the MRI magnets, allowing real-time detection of Bragg peak depth and imaging information, enabling adjustments to the treatment beam parameters and patient positioning for improved dose delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If particle therapy is used to achieve precise dose deposition in tumors, then dose precision is improved, but measurement and verification of in vivo dose deposition becomes difficult
Solution Approach 1:
The patent introduces PET detectors as an intermediary mechanism to indirectly measure dose deposition. The PET system detects positron annihilation photons that are generated when the particle beam interacts with the patient's tissue, serving as a mediator that translates invisible dose deposition into detectable signals for verification
Solution Approach 2:
The patent replaces direct mechanical or physical dose measurement methods with a nuclear physics-based PET imaging system. Instead of using physical probes or mechanical measurement devices in the treatment path, the system uses positron emission tomography to indirectly verify dose deposition through detection of annihilation photons
2Manufacturing precision
If beam energy is varied to spread the Bragg Peak to cover the entire tumour, then dose distribution is improved, but uncertainties in depth calculation increase
Solution Approach 1:
The patent implements a feedback mechanism where PET images are acquired during treatment to monitor the actual position and shape of the Bragg peak. This real-time information feeds back to the control system, allowing verification and adjustment of beam energy settings to ensure accurate dose deposition at the intended depth
Solution Approach 2:
The system performs preliminary PET imaging and range verification before completing the full treatment delivery. By checking the Bragg peak position in advance using PET, the system can identify and correct any depth calculation errors before they result in incorrect dose deposition
3Measurement precision
If real-time monitoring of dose deposition is implemented, then treatment accuracy is improved, but system complexity increases
Solution Approach 1:
The patent combines MRI and PET systems into a single integrated radiotherapy platform. The MRI component provides real-time soft tissue imaging for beam guidance, while the PET component provides dose verification, merging multiple functions into one unified system that reduces overall complexity compared to separate systems
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise, real-time monitoring and adjustment of dose deposition, enhancing the effectiveness of radiotherapy by ensuring accurate delivery of the treatment dose to the tumor while minimizing damage to surrounding tissues.
Implementation Method 1
a Positron Emission Tomography (PET) detector configured to obtain PET data of the treatment beam impacting the patient
Implementation Method 2
the PET data comprises one or both of Bragg peak depth information and imaging information
Implementation Method 3
a bi-planar magnetic resonance imaging (MRI) apparatus, the bi-planar MRI system comprising a pair of spaced apart magnets
Implementation Method 4
Particle therapy, however, has a low uniform dose in the tissue overlying the tumour, then a much higher dose deposition in the tumour due to the 'Bragg Peak'
Data Source
AI summary
A radiotherapy system is configured to determine in vivo dose deposition of a radiotherapy treatment beam. The system includes the following components. A bi-planar magnetic resonance imaging (MRI) apparatus comprising a pair of spaced apart magnets. One of the magnets includes a hole proximal the centre thereof. A treatment beam source configured to generate a radiotherapy treatment beam. The treatment beam source is positioned to transmit the treatment beam through the hole in the magnet. A patient support configured to position a patient with the system so that a treatment target is proximal the treatment beam. A Positron Emission Tomography (PET) detector configured to obtain PET data of the treatment beam impacting the patient. The PET detector is positioned so that a transverse section of the patient that includes the treatment target lies between opposing portions of the PET detector.